Hoary marmot (Marmota caligata) sitting on a rock near the Sahale Arm Trail in North Cascades National Park, Washington, U.S. The hoary marmot is a social mammal closely related to the woodchuck (M. monax).

Astudillo/U.S. National Park Service

Learn about this topic in these articles:

hibernation

...in winter, most of them deeply, although some may emerge from their burrows for short periods on mild winter days. During hibernation they live on fat reserves accumulated during the summer. The
hoary marmot hibernates for up to nine months, its fat reserves amounting to 20 percent of its total body weight. Marmots mate soon after they emerge from hibernation. Gestation lasts about a month,...